Hollowman

As difficult as the motion picture's many shots were, combined they could not match the rigorous demands of the visual effects arena. Verhoeven and his team quickly discovered that the 400 visual effects would be much more complicated than originally anticipated.

The first category of effect employed was known as bio-phase shifting?phase shifting a living creature out of the visible spectrum layer by layer. Today's audience will not settle for merely imagining Sebastian Caine's transformation from normality to invisibility. Viewers demand to experience it, especially when Paul Verhoeven is in command. The director called on every recent breakthrough in visual effects technology and computer graphics imagery and sought the services of the field's leading innovators.

Senior visual effects supervisor Scott E. Anderson says, "Fortunately, Columbia Pictures backed a dedicated research effort on human motion, physiology and animation. The result was a very detailed generic human?our digital body?that showed how we could recreate human physiology."

"There are three transformations in the movie," Verhoeven reveals. "One experiment with a gorilla, and two with Sebastian. Sebastian becomes invisible, and later attempts to return to visibility but fails.

"He disappears and appears in intricate layers. As the radiated fluid enters his system, layers of flesh seem to liquefy. Then the muscular system dissolves, leaving a struggling skeleton wrapped with blood vessels and stuffed with the major organs. Then the organs go. The blood vessels go, leaving only a skeleton. Then the skeleton evaporates into nothingness."

Imageworks' artist, technicians and designers made lengthy visits to medical facilities and schools to examine human bodies, make photographs and drawings, go through anatomical courses and observe autopsies. They had to know exactly what happens when you cut a human body and when you peel real skin. They were apprised on how liquid things are, how much fat there is and even how light reflects off muscles and liquids.

"Through my daughter, who is an art student," Verhoeven elaborates, "we found a museum in Florence, Italy, that is amazing. It houses anatomical wax sculptures with skin peeled off so you can see veins, and you can see muscles and even, partially, bones or whatever lies beneath. You see tendons and the skeleton and the fat. It was all done by a woman in the 16th or 17 century, and they are anatomically perfect."

"We studied her work," jests Verhoeven, "so one of our technical advisors was three or four hundred years old."

To accomplish the transformation sequences, special software had to be written to allow the internal matter of the human form to be realized on screen.

Scott Anderson explains, "Computers typically use surface textures mapped onto the outer edges of an object. It works this way to minimize processing time. Over the years, advances have been made to enable the creation of three-dimensional objects in the digital world, expanding the palette but still only employing surface shaders. We had to develop new techniques so that the details of the human body could be revealed layer by layer.

"With our new software, we can create the muscular contractions, bones, joints and other intricate internal body movements and details. When all the information is fed into a computer, we can then animate the exact movement of the human body and replicate how veins and muscles move beneath the skin. The amount of detail is absolutely staggering."

The solution is a process called volume rendering, in which not only the surface but the entire volume, inside and out, of objects is calculated and produced on screen.

Attempting to explain the technique in lay terms, Anderson continues, "Slicing a previous, typical 3-D digital object in half revealed nothing more than a vacuum inside. In Hollow Man, a 3-D object cut cross-section reveals all the appropriate detail of an object's internal structure. With this method, an organ, such as a human heart, can come to life on screen, gradually beginning as nothing more than the fibers of a capillary system growing and beating. Blood vessels become arteries and veins until layers of muscle develop around them, ultimately forming a fully rendered heart."

"Never before have we been able to look so precisely inside the human body," Verhoeven marvels. "I have never seen anything so beautifully digitalized.

"There are hundreds and hundreds of connected elements inside the body. One tiny movement can affect almost everything. They built a perfect digital body for us, where all the tendons and muscles are perfectly attached so that when an arm moves, you see all the rotating inside. It involves incredible mechanical rules and mathematical formulas."

Anatomy consultants Beth Riga and Stuart Sumida believe that the research accomplished by Sony Pictures Imageworks on behalf of Hollow Man will advance the study of medical anatomy. As educators, they have long sought a richly detailed, precise human model, but funding for such an ambitious project was not available in the scientific and academic community. What was originally designed to create a brilliant visual effect now has the potential to become a valuable teaching tool.

Once the effects geniuses show Sebastian Caine's incredible disappearance, however, there is the massive burden of marking his presence throughout the entire movie. This was the second special effects challenge. The audience and the characters in the story must somehow see his frenzied movements as he frantically fights to preserve him omnipotence.

It is one thing to create a level of dynamic realism in a relatively stationary object, quite another to have an invisible presence be the potent force of the film. Sebastian is, indeed, an unusual lead character. His skin?and everything inside?are invisible. His head and hands are only detectable by the latex sheaths that cover them. Inside his mask's eye holes, there is nothingness.

When Sebastian comes into contact with elements of the real world, however, such as water, smoke, fog or fire, the particular element succeeds in bringing his features into partial visibility.

Verhoeven explains, "When you shoot a scene with the invisible character physically interacting with another person, you film the actors performing the action and then matte the invisible person out. Then, of course, you have a black hole that needs to be filled in digitally. So everything the character has covered needs to be repainted."

The director who added gigantic insects engaging in eye-popping battle scenes to Starship Troopers quickly learned that, "It is easier to add something to a scene than take it out."

To accomplish this goal, actor Kevin Bacon spent much of the shooting schedule covered in green, blue or black paint (with matching contact lenses, wigs, teeth covering and skin-tight leotard) that would enable the visual effects technicians to totally or partially remove him from view.

But worth it, adds Scott Anderson, remembering the awesome challenges of Hollow Man. "Not only did we get to create great images of the human body, but we also had some great surreal and impressionistic moments of the invisible person expressed in his environment. It was a wonderful blend of slam-bam visual effects and some really subtle, beautiful moments."